1. Field of the Invention
The present invention relates to a disk drive for rotating a discoid recording medium such as an optical disk or optical magnetic disk and recording (writing) and/or reproducing (reading) an information signal by moving a pickup along the information recording plane of the discoid recording medium and to a turntable to be preferably used for the disk drive.
2. Description of the Prior Art
A disk drive has been generally produced so far which records and/or reproduces an information signal by using a discoid recording medium such as an optical disk {CD (Compact Disk) or CD-ROM (Read Only Memory)} or an optical magnetic disk (OD). The disk drive rotates an optical disk by horizontally setting the optical disk serving as a discoid recording medium onto a turntable set to the rotating shaft of a spindle motor and applies a laser beam to the information recording plane of the optical disk by an optical head of an optical pickup serving as a pickup. The optical head is moved from the center of the optical disk outward in radial direction so as to write an information signal in the information recording plane or read an information signal previously recorded in the information recording plane.
In the case of this type of the disk drive, it is necessary that the information-recording plane of an optical disk in which an information signal is recorded and an optical head of an optical pickup are set to a predetermined tilt angle or less. This is because the accuracy of reproduction of an information signal greatly depends on the tilt angle of the optical head. In this case, to execute high-density, high-accuracy recording and/or reproducing of an optical disk, it is preferable to set the optical axis of the objective of an optical head vertically (90xc2x0) to the information recording plane of the optical disk. However, because the tilt of an optical disk, verticality of a spindle motor, and verticality of an objective fluctuate, it is difficult to set the optical axis of the objective accurately vertically to the information recording plane of the optical disk.
Therefore, in the case of a disk drive using an optical disk such as a CD or CD-ROM and an information recording medium, the allowable range of a relative tilt between an optical disk and an objective is standardized to 1.20 or less (a tilt angle of an optical disk is standardized to 0.60 or less and a tilt angle of a spindle motor or objective is standardized to 0.60 or less). Moreover, the optical axis of an objective is adjusted in a range between predetermined tilts by tilting an optical pickup on the basis of a state in which an optical disk is set to a predetermined position.
A disk drive shown in FIG. 20 is known as the disk drive having the above disk tilt mechanism. The disk drive 1 is provided with a spindle chassis 2 constituted of a flat frame on whose inside an almost-quadrangular opening is formed and a pickup chassis 3 constituted of a flat frame on which an opening slightly smaller than the opening of the spindle chassis 2 is formed. A pair of shaft portions 3a protruding to the both sides of the pickup chassis 3 in the width direction is provided for the pickup chassis 3 and moreover, a pair of bearing portions 2a for rotatably supporting the shaft portions 3a is provided for the spindle chassis 2. By combining these pairs of bearing portions 2a and shaft portions 3a, the pickup chassis 3 is supported so as to be swingable in the longitudinal direction of the spindle chassis 2.
A tilt driving mechanism 4 is provided for one side of the spindle chassis 2 in its longitudinal direction and the pickup chassis 3 is oscillated in the longitudinal direction of the spindle chassis 2 in accordance with the operation of the tilt driving mechanism 4. A spindle motor 5 is fixed to the other side of the spindle chassis 2 in its longitudinal direction while turning the rotating shaft of the motor 5 upward. A turntable 6 to which an optical disk is set is integrally set to the rotating shaft of the spindle motor 5.
The turntable 6 has the configuration shown in FIGS. 21A and 21B. That is, the turntable 6 is provided with a table 101, a center cap 102, a movable ring 103, a compression coil spring 104, a yoke plate 105, and a magnet 106. The table 101 has an annular mounting portion 101a on which an optical disk 110 is mounted, a recessed portion 101b constituted of an annular recess provided inside of the mounting portion 101a, and a cylindrical boss portion 101c provided for the central portion of the recessed portion 101b. The center cap 102 is fitted to and integrally set to the boss portion 101c of the table 101.
The center cap 102 is constituted of an annular member whose outside diameter is properly smaller than the diameter of the recessed portion 101b, its thickness is set to a value properly larger than the depth of the recessed portion 101b, and its front end is protruded from the recessed portion 101b. An annular concave portion 102a is formed at the front end of the center cap 102 and the yoke plate 105 and magnet 106 are stored in the concave portion 102a. The movable ring 103 is rotatably fitted to the outer periphery of the center cap 102 so as to be movable in the axial direction.
The movable ring 103 has a sleeved ring 103a, an annular end face 103b provided for one side of the ring 103a, and a tapered slope 103c continuously provided for the outside of the end face 103b in its radius direction. One end of the compression coil spring 104 is set on the inner face of the end face 103b of the movable ring 103. The other end of the compression coil spring 104 is set to the bottom face of the recessed portion 101b and the movable ring 103 is always pressed against the front end of the center cap 102 by the spring force of the compression coil spring 104. The movable ring 103 is prevented from being removed by preventing movement of the movable ring 103 by an outward flange portion 102b provided for the front end of the center cap 102. A fitting portion to be fitted to a center hole 110a of the optical disk 110 is constituted of the slope portion 103c of the movable ring 103 and the flange portion 102b of the center cap 102.
The turntable 6 having the above configuration is set to the state shown in FIG. 21A before the optical disk 110 is mounted and the movable ring 103 energized by the spring force of the compression coil spring 104 contacts with the flange portion 102b of the center cap 102. By setting the optical disk 110 to the turntable 6 from the above state and fitting to the center hole 110a, the above stage is changed to the state shown in FIG. 21B and the movable ring 103 is lowered. As a result, the margin of the center hole 110a of the optical disk 110 contacts with the slope portion 103c of the movable ring 103 and the optical disk 110 is centered by the slope portion 103c. 
Moreover, as shown in FIG. 20, a guide shaft 3b and a guide portion (not appearing in FIG. 20) are set to the pickup chassis 3 so as to extend in the longitudinal direction by keeping a predetermined interval from each other in parallel. A slide member 8 of an optical pickup 7 is slidably supported by the guide shaft 3b and the guide portion. Moreover, a not-illustrated rack is fixed to the slide member 8 and a gear located at the end of a head feed mechanism 9 is engaged with the rack. By driving the head feed mechanism 9 and transmitting the torque to the slide member 8, the optical pickup 7 is moved so as to approach to or go away from the turntable 6.
Moreover, a skew sensor 10 for detecting the distance from the information recording plane of an optical disk mounted on the turntable 6 is mounted on the slide member 8. The skew sensor 10 emits light toward the information-recording plane and detects a warpage of the optical disk by receiving the light reflected from the information-recording plane. By changing tilts of the pickup chassis 3 in accordance with a detection result of the skew sensor 10, it is possible to adjust a tilt of the optical axis of the optical head 7a of the optical pickup 7 against a tilt of the information recording plane of the optical disk.
However, in the case of the above conventional disk drive 1, six parts are required because the turntable 6 is constituted by combining the table 101, center cap 102, movable ring 103, compression coil spring 104, yoke plate 105, and magnet 106 and moreover, a lot of man-hours is required. Therefore, there are problems that not only the drive 1 is wasteful but also assembling of the drive 1 is troublesome.
Moreover, because the optical disk 110 is centered to the turntable 6 by lowering the movable ring 103 by the optical disk 110, a high fitting accuracy of the movable ring 103 to the center cap 102 is required. When the accuracy is rough, a problem occurs that smooth movement of the movable ring 103 cannot be secured. Particularly, because the movable ring 103 has a shaft-directional length smaller than the diameter, it is necessary to uniformly press the outer margin of the ring 103 in order to move the ring 103 in the shaft direction. Thus, when the pressure locally works, the movable ring 103 twists and may be caught in the center cap 102.
To solve the above conventional problems, the present applicant previously provided a turntable 120 having the configuration shown in FIGS. 22A and 22B. The turntable 120 is provided with a table 121, a chucking ring 122, a yoke plate 105, and a magnet 106. The table 121 has a mounting portion 121a, a recessed portion 121b, and a boss portion 121c the same as the table 101 does. The chucking ring 122 is fitted to the boss portion 121c of the table 121 and they are integrally set.
The chucking ring 122 is constituted of a tapered cap-shaped member whose outside diameter is properly smaller than the diameter of the recessed portion 121b and its thickness is set to a value properly larger than the depth of the recessed portion 121b, and its front end extrudes from the recessed portion 121b. The chucking ring 122 has an outer-periphery portion 122a, a cylindrical portion 122b, and a boss portion 122c. The boss portion 122c can be fitted to the boss portion 121c of the table 121 and they are integrally constituted by press-fitting the boss portion 122c to the boss portion 121c. 
The cylindrical portion 122b of the chucking ring 122 is integrally formed outside of the boss portion 122c and the yoke plate 105 and magnet 106 are stored in the cylindrical portion 122b. The outer periphery 122a of the chucking ring 122 is constituted of a plurality of fixed pieces 122a1 radially arranged and a plurality of elastic pieces 122a2 respectively arranged between adjacent fixed pieces 122a1. These fixed pieces 122a1 are and elastic pieces 122a2 are respectively connected each other at the front end of the cylindrical portion 122b. Moreover, a proper elasticity is provided for the elastic pieces 122a2 by decreasing the pieces 122a2 in wall thickness and width compared to the fixed pieces 122a1.
In the case of the turntable 120 having the above configuration, the optical disk 110 is centered by the elastic pieces 122a2 having a proper elasticity. Moreover, the fixed pieces 122a1 provided between adjacent elastic pieces 122a2 respectively serve as a guide for inserting the optical disk 110. However, according to the turntable 120 thus improve, the number of parts to be used can be decreased to 4 and thereby, it is possible to improve the assembling-characteristic and productivity. However, an insufficient point is present that a high fitting accuracy between the table 121 and the chucking ring 122 is required.
The present invention is made to solve the above conventional problems and its object is to provide a disk drive capable of solving the above problems by integrally forming a mounting portion on which a discoid recording medium is mounted and a fitting portion to be fitted to a center hole of the discoid recording medium and having an elastic piece to be pressure-welded to the center hole and a turntable to be preferably used for the disk drive.
To solve the above problems and achieve the above object, the disk drive of the first aspect of the present invention uses a disk drive comprising a turntable on which a discoid recording medium used to record and/or reproduce an information signal is mounted and a spindle motor to whose rotating portion the turntable is set, wherein the turntable is provided with a mounting portion on which the discoid recording medium is mounted and a fitting portion fitted to a center hole of the discoid recording medium and having an elastic piece to be pressure-welded to the inner periphery of the center hole and the mounting portion and fitting portion are integrally formed.
The case of the disk drive of the second aspect of the present invention comprises a fitting portion of a turntable set at the central portion of a mounting portion, a plurality of fixed pieces radially arranged, and a plurality of elastic pieces respectively arranged between adjacent fixed pieces.
The disk drive of the third aspect of the present invention comprises a conical fitting portion, wherein a fixed piece and an elastic piece are connected each other at the tapered front end of the conical fitting portion and the other end of the elastic piece is extended outward in radial direction at a mounting portion and formed into a free end.
The turntable of the fourth aspect of the present invention comprises a mounting portion on which a discoid recording medium used to record and/or reproduce an information signal is mounted and a fitting portion fitted to a center hole of the discoid recording medium and having an elastic piece pressure-welded on the inner periphery of the center hole, wherein the mounting portion and the fitting portion are formed into one body.
The turntable of the fifth aspect of the present invention comprises a fitting portion set to almost central portion of a mounting portion, a plurality of fixed pieces radially arranged, and a plurality of elastic pieces respectively arranged between adjacent fixed pieces.
The turntable of the sixth aspect of the present invention comprises a conical fitting portion, wherein a fixed piece and an elastic portion are connected each other at the tapered front end of the conical fitting portion and the other end of the elastic piece is extended outward in radial direction at a mounting portion and formed into a free end.
As described above, in the case of the disk drive of claim 1 of the present invention, the mounting portion and fitting portion of the turntable are formed into one body. Therefore, it is possible to decrease the number of parts to be used and man-hours for assembling the disk drive and securely center the discoid recording medium. Thus, it is possible to provide a disk drive superior in performance stability.
In the case of the disk drive of the second aspect of the present invention, the fitting portion of the turntable is constituted of a plurality of fixed pieces and a plurality of elastic pieces. Therefore, it is possible to provide a disk drive provided with a turntable having a simple structure and capable of securely centering a discoid recording medium.
In the case of the disk drive of the third aspect of the present invention, the other end of an elastic piece connected with a fixed piece at the tapered end is extended outward in radial direction and formed into a free end. Therefore, it is possible to accurately and securely center a discoid recording medium by pressure-welding the free end of the elastic piece to the center hole of the discoid recording medium.
In the case of the turntable of the fourth aspect of the present invention, the mounting portion and the fitting portion are formed into one body. Therefore, it is possible to decrease the number of parts to be used and man-hours for assembling the turntable and securely center the discoid recording medium. Thus, it is possible to provide a turntable superior in performance stability.
In the case of the turntable of the fifth aspect of the present invention, the fitting portion is constituted of a plurality of fixed pieces and a plurality of elastic pieces. Therefore, it is possible to securely center the discoid recording medium though the turntable has a simple structure.
In the case of the turntable of the sixth aspect of the present invention, the other end of an elastic piece connected with a fixed piece at the tapered front end is extended outward in radial direction and formed into a free end. Therefore, it is possible to accurately securely center the discoid recording medium by pressure-welding the free end of the elastic piece to the center hole of the recording medium.